In communication networks, load can vary significantly over time. This is particularly true in machine-to-machine (M2M) communication networks. Such networks may be configured, for example, to support wide area communication of sensor data to Internet-based applications. M2M communications span multiple vertical industries such as transportation, healthcare, utilities, retail, industrial monitoring, banking, and home automation and include a variety of applications within each vertical.
M2M traffic is typically distinct from consumer traffic and is characterized by more frequent but short lived transactions with small payloads. For example, a fleet management application can require transmission of location information every 20 seconds by each vehicle to a central application server with each transaction involving a payload of less than about 500 bytes. Similarly, reporting of health data such as blood pressure or heart rate by medical devices usually involves payloads less than about 200 bytes.
Many communication networks, including mobile cellular networks such as fourth generation Long Term Evolution (LTE) cellular networks, are designed for handling consumer communication applications such as voice, video streaming, video conferencing, web browsing and file transfers where the communication sessions are long lived. Thus a typical session involves establishment of dedicated radio bearers by first using a common random access channel to send relevant control information such as identity of the mobile device followed by actual transmission of higher layer signaling messages and then application data over scheduled dedicated resources. However, use of this current cellular communication technology for M2M applications can result in a disproportionately large amount of signaling traffic relative to data traffic.
LTE networks and other conventional wireless networks such as IEEE 802.11n networks have mechanisms such as rate adaptation and scheduling for dynamically allocating resources to serve multiple users. However, these mechanisms and the underlying techniques for establishing traffic channels via random access channels are designed to operate under a relatively narrow range of load conditions. For very low loads, the network resources are underutilized, and for very high loads, the network resources are insufficient and an excessive number of users may be dropped. While these networks can adapt the transmission rate to meet different link conditions, they do not adapt efficiently to meet widely varying load conditions.
Also, current network design is often focused on maximizing throughput. However, if the application is such that each node needs to only send a small amount of data, as in the above-described M2M communication context, throughput is not necessarily the most meaningful metric.